The production of a waste-water by-product stream which contains ammonia and an acid gas is a common problem in the processing art. The problem lies in the disposal of the stream in an efficient manner whereby noxious materials are not vented into the environment and at the same time costs are kept at a reasonable level. Frequently there is another problem, depending upon location, which is the matter of availability of suitable process water. Especially in the petroleum refining and chemical industries, where large volumes of fresh process water are normally required and large volumes of waste water and by-product streams are produced, are these problems onerous.
In the developing field of fuel gas generation from the pyrolysis of organic and/or carbonaceous solids, efficient waste-water disposal is of particular importance. Suitable raw materials frequently contain sulfur and nitrogen in some form. In the pyrolysis the sulfur is converted to hydrogen sulfide and/or sulfur dioxide, and at least some of the nitrogen is converted to ammonia. A large amount of process water is required to quench the pyrolysis gas and to remove most, if not all, of the sulfur-containing acid gas and ammonia.
Conventional methods known in the art for handling waste-water streams suffer from a number of disadvantages: (1) in general, the size of the units employed is such that the capital cost outlays required for their use is excessive; (2) usually there is such a substantial requirement for high-pressure steam that the operating cost outlay is also excessive; and (3) low-energy heat values are lost or inefficiently utilized, thereby contributing to pollution (heat).